A controlled deflection roll of the type illustrated by the Kusters U.S. Pat. No. 3,023,695, Mar. 6, 1962, is characterized by a rotative cylindrical shell having a cylindrical outside adapted to form a pressure rolling nip with a counter roll, and a non-rotative shaft, sometimes called a core or cross-head, extending axially through and radially spaced from the shell's inside, the shaft having ends extending beyond the roll's ends and adapted to receive force exerted in the direction of the rolling nip. Self-aligning end bearings axially spaced short distances inwardly from the shell's ends journal the shell on the shaft and prevent relative radial movement between the shell and shaft at the bearings. Inside of the shell there is a means for applying in the direction of the nip uniformly throughout the shell's length between the end bearings, a force or pressure between the shaft and the shell's inside.
With the controlled deflection roll cooperating, for example, with a solid counter roll, the contour of the shell can be adjusted by varying the internal force, so as to conform to that of the counter roll when the latter deflects under the nip pressure. With the shaft carrying the reaction, it too deflects, but this is inconsequential because the shaft is inside of the shell. The internal force applied between the shaft and the shell's inside may be via the pressure of a sealed body of pressurized hydraulic liquid extending for the length of the roll between the end bearings as is illustrated by the previously mentioned Kusters patent. A uniform force on the roll's inside may also be applied via shoes bearing on the shell's inside and receiving force from pistons in radial cylinders formed in the shaft and provided with a uniform hydraulic pressure behind the pistons, as is illustrated by the Kusters et al U.S. Pat. No. 3,131,625, May 5, 1964, although not showing the end bearings.
A controlled deflection roll of this type using the end bearings has advantages, but a precisely uniform pressure rolling nip line pressure with a counter roll throughout the shell's length is obtained only if the shell's internal force is exactly balanced by the pressure rolling nip pressure or, in other words, the force applied to the ends of the shaft. Normally, such a condition does not exist.
When the above condition does exist, the end bearings are relieved from radial loading, the shell in effect floating relative to the shaft and providing a nip with a counter roll having a uniform line pressure throughout the entire length of the shell. Under more normal conditions, the end bearings are under radial loading and act as fulcrums so that the shell lengths between the end bearings and beyond the outsides of the bearings deflect differently. The disturbing effects are reflected undesirably in the pressure rolling nip line pressure throughout its entire length, or in other words, from end to end of the shell.
In the case of the present invention the object has been to provide correction for such disturbances throughout the entire length of the rotative shell forming the pressure rolling nip with the counter roll. The correction should be effected in such a way as not to interfere with the outside contour of the roll's shell throughout its entire length.